JPS5920039B2 - Continuous web production control method using β-ray gauge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus and method using a beta gauge for regulating the production of continuous webs of paper-like materials, and more particularly for radiographic inspection. Relates to an improvement in a device comprising a device for continuously monitoring the entire web and comparing the signal generated thereby with the signal generated by a beta gage to control the formation of the web being produced. be.

Typically, the paper manufacturing process involves spreading a material made of a slurry of fibers dispersed in water onto a wire mesh in the form of a cylinder or plate.

This wire mesh forms a platform through which dewatering takes place. The material is directed to the wire mesh by a flow diffuser that converts the exiting flow of material into a flat, shallow flow with uniform velocity across the width of the machine. The web thus formed on the wire mesh is passed through a pressing section where more water is removed and then directed to a drying section where the remaining water is removed. The paper manufacturing process is filled with the foregoing along with other equipment incorporated into huge paper manufacturing machines that operate continuously and produce tons of paper products.

Although the paper manufacturing process carried out by this machine has already been computerized, the paper manufacturing technology is still experimental in nature. Accordingly, an improved method of improving the uniformity and quality of paper produced by a paper making machine is highly desirable. One of the measurements used in the quality control process is the basis weight of the resulting paper product.

One method of determining this basis weight is to use a beta gage that includes a measuring head supported on a monorail and positioned such that a continuous web of paper passes through a gap in the gage. The beta-ray gauge includes a beta-ray source that directs radiation through the web to a detector, which is equipped with an ionization chamber to detect the beta-rays that pass through the paper web.
As the weight of the paper product increases, less beta radiation reaches the detector, and as the weight decreases, more beta radiation is detected. The detected signal is automatically compared to a preset basic signal for the desired weight. The difference between these two signals is measured and any deviation above or below the desired weight indicates a heavier or lighter paper.
Automatic correction is then provided by coupling the comparison controller to a matched regulator of the stock valve, gate positioning device, or flow diffuser to control the distribution of paper material on the wire mesh. I can do it. however,
One of the problems with this approach is that the beta gage measures only one sample area in a continuous web, so any comparisons made may be valid only for that particular sample.

Therefore, some paper manufacturing processes provide scanning beta gauges. However, the problem with this approach is that the gauge moves slowly and never covers the entire width of the continuous web, and even if the gauge does indeed scan the entire width of the web, the cloud chamber of the gauge detector The long response time means that changes in basis weight across this web with the underlying web cannot be measured. Furthermore, the smallest spot size available with a practical beta gage is relatively large, e.g.
．． 3175 cm), while 0
．． Spot sizes of 0.010 inch (0.0254 cm) and smaller are practical in optical scanners and allow measurement of construction as well as basis weight. Composition is the fibrous structure and is directly related to how well the paper can be printed and coated, as well as the paper's tear strength and its visual appearance. Accordingly, it is an object of the present invention to provide a new and improved method and apparatus for more accurately determining and controlling the basis weight of products manufactured in continuous web form.

In carrying out the invention in an exemplary embodiment of the invention, a method and apparatus for controlling the production of unmade products is provided using a beta-ray gauge simultaneously with a radiographic inspection apparatus.

Means are provided for forming a continuous web of material. The beta gauge is utilized to determine the weight of a continuous web and to generate a first signal based on the weight of the web. The first signal obtained from the beta beam gauge is compared to a predetermined reference signal, which is preset for the desired weight, and a difference signal is generated. After inspection by the beta gage, the web is inspected by a radiation inspection device that applies a radiation source across the web to detect the radiation emitted therefrom and obtain a second signal that is also based on the properties of the paper web. . The difference signal obtained from the β-ray gauge is compared with a second signal generated by the radiographic inspection device to obtain a control signal to control the dispensing of material forming a continuous web, either manually or automatically. This control signal can be used for adjustment. Advantageously, a stationary or slowly moving beta gage can quickly and continuously inspect the web over its entire surface, increasing the response time of the radiographic inspection device and increasing its weight. This gives more precise control over the properties of the resulting product.

The present invention uses a beta gauge to measure product basis weight and is applicable to any process or apparatus for forming unmanufactured materials into a continuous web, such as paper, textiles, plastic film, etc. It is directed towards.

The invention will be described and exemplified in connection with one of its important applications: paper. Thus, while one form of paper making machinery and process is described for illustrative purposes, it will be apparent that other types of machinery and processes may be used in accordance with the teachings of the present invention. It will be.
Referring to FIG. 1, a paper making machine or machine is provided and generally designated by the reference numeral 10.

Paper making machine 10 includes a flow spreader 12 to which paper material consisting of a slurry of fibers dispersed in water is fed. Flow diffuser 12 provides a means for converting the flow of paper material conveyed thereto in a pipe into a flat, shallow flow having a uniform velocity across the width of paper making machine 10.
Flow diffusers typically include a headbox component to further smooth velocity changes in the incoming flow of paper material and are designed to control the level of disturbance in the material before it reaches the forming stage. Flow spreader 12 imparts paper material to a running woven wire mesh 18.

This wire gauze 18 is designed to control the rate and manner in which water in the material is dewatered through the wire gauze. A continuous paper web 14 is thus formed on a wire gauze 18 of what is commonly referred to as a fourdrinier machine 16. The fourdrinier paper machine described has a wire mesh belt supported by a series of rolls and a separate dewatering control device in a horizontal position between the dewatering process. Fourdrinier machine 16 can have various shapes and may include a screen at the top, not shown. Furthermore, as explained, the invention is not limited to the use of fourdrinier machines, but also other wire meshes, such as cylindrical machines, where the material is applied to the outside of the roll by a "butt". The same applies to mold supports. The continuous web 14 is passed from the fourdrinier machine 16 to a press section 20 where some of the water in the slurry is removed from the web 14 and the remaining water is dried in a drying section 22.

Once most of the moisture has been removed, web 14 is passed through beta gage 24. The beta-ray gauge 24 has a detector 28 disposed on one side of the web 14 and a beta-ray source 26 disposed on the other side of the web 14 in alignment with the detector 28.
Beta gauge 24 operates to measure the basis weight of continuous paper web 14. Typically, the beta gage 24 is supported on a monorail (not shown) and positioned so that the web 14 passes through the gap of the apparatus between the beta source 26 and the detector 28. As the weight of the web 14 increases,
Fewer beta rays reach the detector, and as the weight decreases, more beta rays are detected and a larger detection output signal is generated. The output of the detector 28 is connected to a comparator 36 which also has a reference potential power supply 38 applied thereto. Therefore, the detected β-rays from the β-ray source 26 are transmitted to the detector 2.
8 to a comparator and is automatically compared with a preset reference power source 38 for the desired weight for the paper web 14. The difference signal between reference signal 38 and detector signal 28 provides an output at comparator 36 which indicates whether a given web is heavy or light. In the known apparatus, the output of the comparator provides a differential signal from the comparator 36 to the controller, which signal can be used in some way to control the flow spreader dispensing the paper material, thereby reducing the paper web. can be used to modify the weight of

However, this gives only one point in the web, and if the web happens to be unusually thick at the measured point, but thinner and uneven at other points, a false correction will be given. Furthermore, even if the beta gage scans the web, its movement is too slow to provide anything other than course adjustment to the flow velocity provided by the flow diffuser 12. In accordance with the present invention, an optical inspection device 30 (which may include selective infrared or ultraviolet light waves) is used to augment the beta radiation gauge 24.

Optical inspection device 30 includes a light source 32 applied across a continuous web. The receiver 34 passes through the web to the light source 3.
A light source 32 to receive the radiation emitted from 2.
They are arranged in a uniform arrangement. The signal generated by the receiver 34 is in fact indicative of the transmission properties of the web, which also depend on the basis weight of the web. The detected output of receiver 34 is amplified by amplifier 40 and provided to comparator 42 along with the difference signal from beta line gauge 24 at the output of comparator 36. The output of comparator 42 is illustrated by waveform 50 in FIG. 3, and the portion of the waveform that exceeds a typical level 52, which is the desired thickness and basis weight of continuous web 14, indicates the failure of paper web 14. It shows uniform thickness. Waveform 50 from comparator 42 is provided to controller 44 which controls the output of flow spreader 12 across the entire width of the web to provide a more uniform paper product. Automatic correction of weight can be obtained by coupling controller 44 to a stock valve, gate positioner, density regulator, etc. that controls uniform distribution of paper material to Fourdrinier machine 16. . FIG. 1 illustrates the use of a transmission inspection device.

However, since increasing the density of the web can also increase the reflection from the web in some materials, reflective type devices may be used in some applications where the receiver is placed above the web. Light source 3
is positioned above the web 14 to receive the reflected radiation emitted from the web resulting from the scanning of 2.
Whether a reflective or transmissive mode of operation in an optical inspection device is used depends on the type of material being formed into the web and the particular application. FIG. 3 illustrates the use of a gate control system 48 into which paper material is conveyed via pipe 46 to a plurality of orifices 49 which are controlled by control system 44.

Therefore, the dimensions or holes in orifice 49 are
0 is controlled by the control device 44. The signal 50 can be divided into several lanes, each containing one orifice 49, so that the overall width of the web can be controlled. It will be appreciated that the type of control used will depend on the particular type of flow spreader and the various flutings in the spreader that uniformly spread the paper material onto the wire gauze 18 in the paper manufacturing process.

As illustrated in FIG. 4, the optical inspection device is preferably in the form of a laser scanner, in which a laser 52
The laser beam from is scanned across web 14 by rotating drum 54, forming a beam 32 as shown in FIG. The receiver portion 34 shown in FIG. 1 consists of a collection rod 56 and a suitable detector such as a multiplier phototube 58 at one end for detection, as shown in FIG. The device detects radiation from the laser beam that passes through the web 14. Instead,
As illustrated in FIG.
The web 14 may include a plurality of stationary light sources 60 spaced along the top of the web 14 and a plurality of cooperating photodetectors 62 spaced along the underside of the web 14. good.
The light source 60 may constitute a single light source covering the entire width of the web, or a photocell 62 to which a single light source is fixed.
It will also be clear that the can be used below to scan across the top of the web for detection purposes. The light source may also be in the selective infrared and ultraviolet range to accommodate different types of webs. Similarly, as previously explained, the optical inspection device may be operated in reflective mode. By augmenting the beta gauge with an optical inspection device, the advantages of both devices are used to actively control the web forming process.

The accuracy of the beta gage in one particular area is increased by the inspection light source covering the entire area of the web.

As the web 14 is traveling, the web is scanned repeatedly and rapidly by the optical inspection device, otherwise essentially the entire surface of the web cannot be covered, i.e., scanned quickly enough to provide the desired control. This cannot be achieved with beta-gauges that cannot provide the required specific resolution. Although the illustrative apparatus uses automatic correction in the forming process using a closed-loop controller,
It should be understood that the resulting signals can be displayed or otherwise used, for example, for manual control, for evaluating the quality of the output, etc.

The present invention is limited to the embodiments chosen for illustrative purposes, as other changes and modifications to suit particular operating conditions and environments will be apparent to those skilled in the art. This invention is intended to include all changes and modifications that do not depart from the true purpose and intent of the invention.

[Brief explanation of the drawing]

1 is a schematic block diagram exemplarily shown in the form of a block having the functions of one type of paper-making machinery embodying the invention; FIG. 2 is a schematic block diagram for controlling the formation of a paper web; An elevational side view exemplarily showing a gate control device that can be used in the flow diffusion device illustrated in FIG. Comparator 42 of FIG. 1 is useful for
FIG. 4 shows one type of radiographic inspection device that can be used in the paper manufacturing device of FIG. 1, and FIG. 5 shows the waveform of an electrical signal of the type generated by 2 is another form of radiographic inspection device that can be used in the process.

Claims (1)

[Scope of Claims] 1. A method for controlling the production of products formed on a running web using a β-ray gauge together with an optical inspection device for inspecting the running web, the method comprising: dispensing raw material, sampling the basis weight of said continuous web thus formed by passing it through a beta gauge, and determining a first weight based on the weight of said web as measured by said beta gauge; generating a signal to the beta line gauge; and comparing the first signal from the beta line gauge to a preset predetermined reference signal for a desired weight to generate a difference signal. In the method having each step, the entire web is continuously inspected by an optical inspection device by irradiating a light source across the entire web and detecting the light emitted from the light source, and the optical inspection device continuously inspects the entire web to detect the light of the web. providing a second signal based on transmission or reflection properties; comparing the difference signal and the second signal and obtaining a control signal therefrom; and controlling the control signal to control the basis weight of the continuous web. A continuous web manufacturing control method using the β-ray gauge, comprising the steps of: adjusting the distribution of raw materials forming the continuous web using the β-ray gauge.